It is very important in connection with any catheter arrangement for withdrawing a sample of body fluid to ensure that the sample is not contaminated in any way. Customarily, the catheter is a flexible tube of some kind which is inserted into the body cavity and fluid is withdrawn through this tube. The opening to the body cavity is often contaminated with bacteria and the tube, in being inserted through the opening, accumulates bacteria which in turn are introduced into the specimen being withdrawn.
In order to overcome this, it has been proposed to use an inner tube which is maintained in retracted position while the outer tube is being inserted into the body cavity. When it is desired to take the sample, a suitable collection means such as a syringe is attached to the inner tube and the inner tube is moved forwardly into the body cavity. Since the inner tube is spaced from the distal end of the outer tube while the latter is being inserted into the body cavity, it is possible to keep the inner tube relatively free from contact with bacteria. The problem with such an arrangement is that if the distal end of the outer tube being inserted into the body cavity is open, a certain number of bacteria are forced into the end of the outer tube and these can, in turn, be collected by the inner tube as the inner tube is forced forwardly through the distal end of the outer tube. While it has been proposed to have the distal end of the outer tube which is inserted into the body made so that it is normally closed and is opened only when the inner tube is shoved forwardly, there is a problem in connection with preventing contamination of the inner tube from other sources than that of the body cavity. In order for the inner tube to be able to be moved forwardly beyond the distal end of the outer tube, it is necessary to have the inner tube substantially longer than the outer tube. This raises a danger that the inner tube can be accidentally withdrawn from the outer tube. Even though the inner tube may be packaged with the major length thereof already disposed in the outer tube, a portion of the inner tube inevitably projects beyond the proximal end of the outer tube and raises the possibility of the inner tube being withdrawn completely in the course of removing the catheter from the package. For example, if the assembled catheter is disposed within a package, as is normally the case, a nurse opening the package may instinctively pull the inner tube out since it is already projecting a substantial distance out of the outer tube. Once she does this, it is very likely that the inner tube will be contaminated before it is placed back in the outer tube. This may result in not only contaminating the sample, but may also cause infections to be introduced into the patient when the inner tube which has been handled by the nurse is inserted through the normally closed end of the outer tube into the body cavity.
The problem of avoiding contamination of the sample when drawing the same is particularly important in connection with ileac diversions in which the ureters from the bladder are connected directly to a section of the ileum, forming an ileal conduit, which in turn has a restricted open end extending through a cavity of the abdominal wall. Normally, a collection bag is attached to the ileal conduit through a suitable fitting and the urine passing out through the opening or stoma of the ileal conduit is collected in the bag. When it is desired to take a sample of the urine within the ileal conduit, a tube is inserted so that it extends through the stoma into the ileal conduit. It is obvious that, with such an arrangement, the presence of bacteria within the stoma is very great and, unless some precautions are taken to avoid contamination of the collection tube by the bacteria present along the walls of the stoma, a contaminated urine sample will be obtained.